Environment

2:58 pm

Fri May 24, 2013

Reinventing Farming For A Changing Climate

This is SCIENCE FRIDAY. I'm Flora Lichtman. You've likely heard of the legendary explorers Lewis and Clark, but maybe not of the U.S. Army explorer Stephen Harriman Long, an engineer who led a scientific expedition through the Great Plains 15 years after Lewis and Clark.

His expedition traveled through Oklahoma, Kansas and Nebraska. And what did his crew make of "America's Breadbasket"? A place wholly unfit for cultivation or agriculture, they said. On a map, the explorers labeled the Great Plains as the Great American Desert.

Irrigation changed all that, of course, but can it last? Rain's been sparse this year on the plains. Much of Kansas and Nebraska are suffering extreme drought. Meanwhile, groundwater is drying up due to over-pumping, and in some areas, farmer's wells are dry and they can't irrigate their land.

Farmers are already adapting to these changes, and scientists - like some of my next guests - are out there measuring leaves on experimental crop plots, taking satellite measurements of water sources or using new genetic techniques to map a course for the future of farming.

If you would like to get in on the conversation, give us a call. Our number is 1-800-989-8255. That's 1-800-989, if you have question about dryland farming. Now let me introduce my guests. David Wolfe is a professor and chair of Atkinson Center Climate Change Group at Cornell University. He joins us from a studio on campus. Welcome to the show, Dr. Wolfe.

DAVID WOLFE: Hi. Nice to be here.

LICHTMAN: David Nielsen is a research agronomist with the Agricultural Research Service, a division of the USDA, in Akron, Colorado. And he joins us by phone. Welcome to SCIENCE FRIDAY.

DAVID NIELSEN: Thank you. Nice to be with you.

LICHTMAN: Dr. Wolfe, you were involved in the national assessment of climate change and agriculture a few years back. Give us a sketch of what changes we might expect to see in the next 50 to 100 years.

WOLFE: Well, certainly, a new - you know, a lot of new challenges for farmers. I often say to farmer groups that, really, you know, you're the first generation of farmers who can't depend on historical weather records for where you live to tell you what to grow, when to grow it and how to grow it.

So farmers have to just be really much more on their toes, not only with being in tune with, you know, weather forecasts, but also with knowledge of the climate change forecast for their area. And, of course, it varies quite a bit by region of the country, but there are some broad, sweeping things, at least for large regions.

For example, a lot of the high latitude areas, where there's actually some opportunities with the longer growing season that farmers could take advantage of, but it's risky, because we are seeing - while we do see longer frost-free periods, sometimes the growing season has been cut short recently by heavy spring rainfall events that delay planting.

New pests and diseases moving northward is a big challenge for the higher latitudes. When we get down to the Southwest, Western U.S., southern part of the Great Plains that you mentioned, there there's real issues with drier conditions and, you know, aquifers drying up, that sort of thing.

And even in the higher latitudes, where rainfall may not change that much, crop demand for water will increase. As we have this longer growing season and we have warmer temperatures in the summer, crops will need more water. So even in areas - unless the rainfall actually kept up with the warming summers, we're likely to see more summer droughts, even in the higher parts of the country.

LICHTMAN: A longer growing season, because of climate change raising temperatures. Do I have that right?

WOLFE: Yeah, definitely. So the - and we definitely see a very, you know, a marked signal of that across the Northern Hemisphere, the frost-free period in general expanding. On the other hand, that - you know, it's not so simple of that. For example, in Upstate New York, where I'm at, at Cornell University, apples are a very big crop. We're second or third in the U.S. in apple production. And we've seen more spring frost damage recently with this longer growing season and warmer winters.

But the plants are blooming way too early in some of our warmer winter years and more variable winters and jumping the gun, you might say, and then still getting hit badly by a spring frost event. So - but there's a general trend for that. So, definitely.

LICHTMAN: David Nielsen, how are farmers in the Great Plains adapting to - or how are they dealing with the drought?

NIELSEN: Well, there's actually two very different kinds of agriculture in the Great Plains. The one is, as you mentioned, irrigated agriculture, which a lot of that is out of the Ogallala Aquifer, or it's also called the High Plains Aquifer. And in some parts of that region, as you've stated, the wells are drying up in parts of Texas.

But in parts of Nebraska and Colorado, they've had some significant safeguards against that, and it happened a lot of new drilling of wells for quite some time. And so the aquifer is fairly stable in that part of the country.

So they're - the irrigated farmers are adapting by sometimes changing to a crop that has less water uses, less demanding of water - for example, planting some of these center pivots that are generally in corn production into wheat production. Or they may be going to limited irrigation responses, where they don't apply enough water to get the maximum yield, but they apply smaller amounts at various times that are critical to the crop development - for example, in corn, near tassling and silking and early grain-filling time. And they'll get a lot more response - or they'll get more yield for the amount of water they put on. The other kind of agriculture is dryland or rain-fed agriculture. And, of course, those farmers are subject to whatever falls as precipitation during the growing season here.

So they adapt by using no-till systems that have higher precipitation storage efficiencies during the non-crop period, so they can store the maximum amount of water in the soil when the crop isn't growing, so that...

LICHTMAN: Tell us what the no-till system is.

NIELSEN: What a no-till system is? Well, that's a system in which the crop residues from the previous crop are not manipulated in any way. There's no tillage going on to control weed growth or to turn the soil at all, and that crop residue - generally, if it's in a standing position, as well - has a very high ability to suppress evaporation and out here to catch snow and increase the storage soil water profiles. (unintelligible) tilling.

LICHTMAN: It sounds like a layer of mulch.

NIELSEN: Yeah, there's a layer of mulch there, too. Besides the standing stalks and stems, there's the other residue that comes out of a combine after it's harvested that acts as a mulch on the surface.

LICHTMAN: And is the idea that if you don't till, then less water evaporates, because you're not exposing as much of the soil underneath to evaporation, to the air?

NIELSEN: Well, there's two things. One is what you've just said here. You haven't brought new, moist soil to the surface that can be readily evaporated. The other thing is, as I've said, you leave the standing residue up, it shades the soil. It slows the air movement over the soil, and so evaporation rates are subsequently much lower.

WOLFE: There's even another feature, if I might add to that...

LICHTMAN: Please.

WOLFE: ...that soil conservation approach, and it's that you build up the organic matter in the soils with a no-till system, because every time you go out and turn the soil, whether you're a gardener or a farmer, you pump oxygen into the soil, which hastens the decomposition of organic matter in the soil, and it goes up as CO2 into the atmosphere, in fact.

So by reducing tillage, you start to build organic matter, which creates soils of better water-holding capacity and better drainage. So it kind of can buffer farmers from at least short-term water stress drought periods and short-term heavy rainfall events.

Plus, it's got this mitigation feature. That organic matter is largely carbon. So that's carbon that's now in the soil. That could have been in the air as CO2, the greenhouse gas.

LICHTMAN: It seems like an energy saver, too. You wouldn't have to actually go around tilling.

WOLFE: Yeah, lower fuel costs, for sure.

NIELSEN: Yeah, it certainly is.

LICHTMAN: If you want to ask a question about the future of farming or farming in drought, our number is 1-800-989-8255, 1-800-989-TALK. David Nielsen, I was reading that some plants are more efficient than others with water, and you sort of alluded to this. Corn is kind of thirstier.

NIELSEN: Well, it is true, corn will use a lot of water if it's available here. But I think what you may be referring to is the difference in crop type and how they turn water and carbon dioxide into carbohydrates. And two general classes of plants are C3 and C4 plants. And they're called C3 and C4 plants because the first product of photosynthesis is either a three-carbon chain or a four-carbon chain, and the C3 plants, compared with the C4 plants, are not very efficient.

A C4 plant would be like corn or grain sorghum or a proso millet. In this country, a lot of people don't know what proso millet is, but it's the primary component of birdseed. They're very efficient. They can - those C4 plants can produce about, oh, 550 to 650 pounds per acre of grain for every inch of water that's used. In contrast to that, the C3 plants, like wheat, would produce about 250 to 300 pounds, so half of the rate of production, 250 to 300 pounds per acre for every inch of water used.

But within the C3 plant species, there are legumes, and then there are oilseeds. And legumes have a higher protein content than the seed. It takes more photosynthetic energy to make that protein than it has to make the starches in the grain crops.

And there's also oilseeds in the C3 category, and it takes even more photosynthetic energy to make the oil in the seeds. So legumes can produce about 170 to, say, 200, 250 pounds per acre per inch in the oilseeds, about 150 to 180. So you see there's a wide range there, from like 150 pounds per acre per inch per water use, up to 650 pounds per acre per water use.

So if you wanted to make the best use of a limited water supply, you'd probably want to, you know, plant a C4 plant. And in the Great Plains here, that proso millet that I said was primarily used for birdseed in this country, is a highly efficient plant and with a very short growing season. And so it could get by with very little water. It's a species that would be very well adapted to dealing with drought periods here.

But, again, for a farmer, the problem is there's not a huge market for the millet seed. If it was - if this country had a taste for it and it was used more for human consumption and there's a bigger market, they certainly could grow a lot more of it out here.

LICHTMAN: So if we wanted to be eco-conscious in the water sense, more millet, David Wolfe?

NIELSEN: Yeah.

WOLFE: Yeah. I think, you know, I would go along with that. One thing to keep in mind, though, is that this water use efficiency is, you know, how much can you produce given a short amount of water. But the corn - a crop like corn still is not, you know, necessarily that much more tolerant to drought than some other crops.

So if there's really a severe shortage of water, unless we make advances in breeding, et cetera, to build better, real drought tolerance to it, they still suffer and their yields are much less than they would be otherwise, but there is that efficiency factor.

And actually a big place where there's been lots of water savings - I've got a project in Ethiopia now, where farmers have been shifting from wheat to potatoes because potatoes have a very short growing season compared to the wheat, and they can get a lot more calories and protein per unit water and with a short growing season than they could with the wheat.

So just getting varieties that just - even with - of the same crop, finding varieties that are shorter growing season, they tend to, you know, use up less water because they're out there for a shorter period of time. But, again, then you're not really taking advantage, in the higher latitudes, of this potential for longer growing season varieties because of the longer frost-free period which could increase your yields.

You know, in general, longer growing season varieties are out there longer and take up more carbon dioxide and produce sugar from photosynthesis, so they produce more. So challenge for farmers.

And then, you know, the big challenge, of course, is, just like any of us thinking about climate change, is trying to detect the signal of climate change against the noise of, quote, "normal weather variability" and when it's really time to think about making some kind of adaptation that might have some cost risk with it.

LICHTMAN: This is SCIENCE FRIDAY from NPR. I'm Flora Lichtman.

And I'd like to bring out another guest now, who's actually manipulating the genes of plants to come up with more robust crops, but this isn't your garden variety GMO. Sally Mackenzie is a professor of plant science at the Center for Plant Science Innovation at the University of Nebraska in Lincoln. Welcome to SCIENCE FRIDAY, Dr. Mackenzie.

SALLY MACKENZIE: Thank you very much.

LICHTMAN: Tell us what you're doing in your lab.

MACKENZIE: So, actually, you know, the challenge that's put before us, as you were just hearing from your other guests, is a big one, because we have a societal response to agriculture that, right now, has not been really embracing genetic engineering to the level that perhaps we would have liked early on. And at the same time, we need to expedite our plant breeding capability so that we can breed more rapidly and more efficiently to meet the needs that are now before us with climate change.

So my laboratory actually works in an area of genetics known as epigenetics. Where we're able to actually manipulate a plant to - into believing that it's actually seen abiotic stress: stress to heat or cold or to drought. But the plant actually hasn't seen that stress. We're doing this with a genetic manipulation, and it actually puts the plant into a different state, if you will.

That plant is in a hyper-defensive state, and interestingly, that causes a change, not at the genetic level in the plant, but basically what we call the epigenetic level where it changes the methylation patterns in DNA. So DNA itself isn't changed, but the decorations, if you will, on that DNA are altered.

And in response to that, when we breed with that hyper-enhanced state, what we find is that the crops that emerge from that method actually have a greater enhanced vigor and a greater enhanced growth rate, above-ground biomass, ability to produce and adapt to their environment. So, serendipitously, we found that plants have their own capabilities inherent to them in adapting to stress that we might be able to exploit.

LICHTMAN: So let me see if I have this correct. So you take a plant - let's just say it's a tomato - and you stress it. So you don't give it as much sunlight, or maybe you don't give it as much water, and you see a change in the way that it grows, right? And then you...

MACKENZIE: Well...

LICHTMAN: Go ahead. Correct me as I go.

MACKENZIE: No. Actually, we don't have to subject the plant to that stress. What we do is, in the lab, we genetically manipulate the plant by actually fooling it...

LICHTMAN: Oh.

MACKENZIE: ...into thinking it's seeing that stress so that once we've put that plant into that state and we breed with that plant, we actually have this enhanced growth capability, but, in fact, we never had to have the plant in exposure to stress. What we do is in the lab, we genetically manipulate the plant by, actually, following it into thinking at seeing that stress so that once we've put that plant into that stage and we breath with that plant, we actually have this enhanced growth capability. But in fact, we never had to have the plant in exposure to stress. So what this gives us is a new way of breeding, if you will, it sort of revolutionizes the way we do breeding by capturing value and what we call the epigenetic or epigenome of a plant so that we're able, actually, to use this methodology to make the plant think it's seen stress when it hasn't. It proves as a breeding method so that we hope that we can actually breed plants that are going to be better able to cope with that stress as we release these new cultivars that come from this technology.

LICHTMAN: This sounds Mendel 2.0.

MACKENZIE: Actually, it sounds a little more like Lamarck, you know, during those days that we were formulating our understanding of genetics. You know, there was another theory out there, and it turns out that Lamarck might have been a little bit right.

LICHTMAN: Well, there you go. Much more on this topic when we come back. Stay with us. This is SCIENCE FRIDAY from NPR.

(SOUNDBITE OF MUSIC)

LICHTMAN: This is SCIENCE FRIDAY. I'm Flora Lichtman. We're talking this hour about climate change and the future of farming with my guests. David Wolfe is a professor and chair of the Atkinson Center, climate change group at Cornell University, David Nielsen is a research agronomist with the Agricultural Research Service, a division of the USTA in Akron, Colorado and Sally Mackenzie is a professor of plant science at the Center for Plant Science Innovation at the University of Nebraska in Lincoln.

And when we dropped off, Sally, we were talking about how you actually get these plants. And I wondered, you said that they grow bigger and have more biomass. This make them - this method, actually, makes the plants more resilient to stress too.

MACKENZIE: So you know, this is a new technology, and we haven't fully tested it. But we believe that in fact this maybe one approach to expediting the breeding for stressed tolerance, and largely, that would be through this enhanced figure, as well as through manipulating, basically, a plant's ability to sense stress. So plants - what we've learned from this system is that plants actually sense a lot of their stress and respond to it through their chloroplast which is the component of the cell that's responsible for photosynthesis, as well as for detecting light. We didn't know that before, and it turns out that it's through the chloroplast that we can create this enhanced growth state in these plants.

So we're hoping that through manipulating this or using this methodology, we will be able to find a away to actually help plants to enhance their response to that stress. But at this point, all we've really been able to demonstrate is this enhanced growth, above ground biomass, enhanced yield. So, of course, you know, agriculturally, this is of tremendous interest. And yeah, it open s a how new avenue, I think, for expediting breeding.

You know, there are two important parts to where I'm telling you. One is that the technology's I'm describing are non-GM. They're not involving genetic engineering. And two, this gives us an opportunity, now, to arrive at enhanced growth states in, you know, three or four generations where normal plant breeding is going to take you 10 to 15 generations before you have a truly new and enhanced variety. And those are two key components that we need right now, I think, to address climate change. It's something that people will adjust to and accept and something that will expedite the process considerably.

LICHTMAN: David Wolfe, do you find that farmers are enthusiastic about staying on top of climate change or thinking about it?

WOLFE: Well, I've seen - I've been, you know, working with them since 1990 or so on this topic. And as the evidence of climate change is becoming more apparent right on their own farm, I think they are becoming, definitely - particularly, on the adaptation end, you know, really trying to figure out ways to cope with it just as part of being, you know, a good business person. They're becoming much more aware. And so they're very open to it.

The challenge they have, like I mentioned before, is really trying to determine - even the climate scientists have a hard trouble with this. You know, what is really part and parcel of climate change, and why this quote, "normal bad weather?" And also what they're seeing on the ground is more just that the climate and weather, year to year, is more variable and more unpredictable than it used to be. Now this is not something that climate scientists are quite ready to confirm with a higher degree of certainty. There's a lot of dispute in the climate science community about whether the variability of the climate, per se, is changing. But on the ground, a lot of farmers feel like it's not just that we're seeing a gradual trend for dryer years or hotter years, but that this year, it was, you know, wetter than I've ever seen in the spring. Next year, it's dryer than I've ever seen in the middle of summer.

So this idea of having, you know, plant varieties, for example, that are better able to detect what stress is being imposed on them and then have, you know, the genetic capability. There are types of genes called promoter genes which can then, you know, turn on sort of the drought and defense mechanism, if that's what the plant's experiencing versus the high temperature stress mechanism, if that's what the plant is sensing. So we really need a lot more, kind of, diversity, both in terms of what the farmers plant out there to sort of hedge their bets and also in terms of the actual varieties and the genetic makeup of those varieties, having varieties that are more diverse, more quick on their feet, you might say, in terms of responding to stress because of this unpredictable nature of climate change.

LICHTMAN: Sally, what plans have you done this with, this crossing?

MACKENZIE: So we've used this technology with sorghum and with tomato, soybean, wheat, rice, and in all of those cases we've seen this type of enhancement of growth and very similar trends. So this seems to be a language that they all know, and I won't be surprised if this extends into our tree crops and, you know, and into basically many avenues of agriculture.

I think that this was something we stumbled upon, that we simply didn't know was in the, you know, the toolbox of a plant for adjusting its growth rate in response to its environment. So it's a very exciting discovery that I think could have impact in addressing some of these issues.

LICHTMAN: I was amazed to learn that a plant can pass down something like this, you know, that they can pass down a memory of an experience.

MACKENZIE: Yes. And so that is really the area of epigenetics and what it's teaching us, is that aside from the gene changes that we inherit from a mother and a father and that plants as well inherit, that they can have experiences during their lifetime that can actually change the proteins - the - make changes on the proteins that interact with the DNA in such a way that there can be a memory. And if a plant sees drought early in its lifetime and then adjusts from it and later sees drought a second time, it will be pre-adapted or already acclimated to that drought condition.

And likewise, we see this in the work that my laboratory is doing where we can, as I said, fool the plant into seeing - thinking it's seen stress. And generations later we have maintained that same condition within the plant. So like I said, this is a very new day for breeding if this is right because it opens new avenues for us that we have not been able to access in the past.

LICHTMAN: Let's go to the phones for a quick phone call. Luke in Reno, Nevada. Welcome to SCIENCE FRIDAY. Luke, are you there? Maybe not. Let's see. What about Terry in Gainesville, Florida? Terry...

TERRY: Hi, Flora. Can you hear me OK?

LICHTMAN: I can hear you. Do you have a question?

TERRY: Flora?

LICHTMAN: I can hear you.

TERRY: Can you hear me OK?

LICHTMAN: I can. Go on. Well, let me summarize 'cause I think Terry can't hear me is what's happening. The West - he says the West used to have a lot of buffalo grass, which basically supported cattle. Should we go back to that? David Nielsen, do you have any thoughts on this question?

NIELSEN: I'm wondering if he's referring to changing the Great Plains back to a game preserve. There was a proposal being - put forth by a couple of professors from Rutgers about 20 years ago called the Buffalo Commons where they were actually saying that the great experiment of agriculture in the Great Plains has been shown to be a total failure and it should all be turned back into just a game preserve for the buffalo because that's in its natural state, what best thrived out here.

And I guess my response to that is we do have thriving agriculture out here now. And these professors, their names were the Poppers, and one of them has actually come out here and said, well, maybe he misjudged about what it was like 'cause he wrote that thesis without having yet revisited the Great Plains. And as I've tried to mention before here, the use of conservation tillage or no tillage and careful management of the residues has made agriculture significantly better-adapted to this somewhat fragile region that is limited in its water availability. But successful agriculture is possible out here, whether it's dry land or irrigated agriculture.

LICHTMAN: Thanks. I think we should leave it right there. Let me thank my guests. We'll have to continue the conversation another time. David Wolfe is a professor and chair of the Atkinson Center, a climate change group at Cornell University. David Nielsen is a research agronomist with the Agricultural Research Service, a division of the USDA. And Sally Mackenzie is a professor of plant science at the Center for Plant Science Innovation at the University of Nebraska in Lincoln. Thanks to all of you for joining me today.